Editorials

Designing A Good Interface

Feedback in StarCraft is provided in a novel fashion -- through audio feedback from the units themselves. Tank drivers who are ordered to do something impossible, such as fire on an airborn target, will quip, "No can do!" Likewise, if the order goes through successfully, they will give some other confirmation phrase. This not only provides instant feedback to the player, but it is also very entertaining. Many players find themselves clicking on their units just to see what will happen next.

StarCraft offers some affordances. Icons that represent actions for a unit to take are made to design something suggestive of their function -- the attack icon is a target reticule, the patrol icon is an arrow, etc. Some of the more abstract actions possible are difficult to create, or to map into everyday experience. For instance, none of us has any real-world experience with mutating alien life forms into a tougher, faster life form. Therefore, there is a learning curve that goes along with learning to play StarCraft, but the tutorials that accompany the various single-player missions will walk the user through new possibilities that are not immediately obvious.

StarCraft helps the user form a good cognitive map in this fashion. While it is not immediately obvious that an academy is necessary to create marines with flamethrowers (known as FireBats), the game will actually instruct the user on how to build an academy, and what it can be used for the first time it is encountered. Similarly, anytime something that does not have an obvious affordance to it is encountered, a pop-window appears, explaining its purpose. The game's interface helps the user create a good cognitive map of its possibilities, while slowly weaning the user off of that help. In no time flat, the user is clicking away at a frantic pace.

Figure 6

Not so with Star Wars: Rebellionviii by LucasArts. Billing itself as a real-time strategy game, Rebellion made some design errors which made the game nearly unplayable, and very unsuccessful in the market place. In Design of Every Day Things, Donald Norman frequently jokes about poor design, saying that "it probably won an award" -- and this appropriate to Rebellion. The interface is aesthetically very appealing, and is inspired by the well-known style of the Star Wars movies. However, the visual appeal is entirely at the expense of usability. The main display room is a stunning galactic panorama, with advice and feedback given by C-3P0, or his evil Imperial counterpart, depending on which team you are playing. (Figure Six)

The tiny computer screens, as well as the multiple boxes on every side of the panorama, call up additional screens of information or possible commands. Yet, none of them are the most important functions of the game. To get to the screens in which combat might occur, buildings and resources are constructed, or missions are embarked on, and the player has to click on a screen element that is not obviously a control -- while all around it are screens, boxes, and buttons that obviously ARE controls. This is the opposite of an affordance, it is an obfuscation, and one which is made only for the sake of aesthetic appeal.

Figure 7

When the meat of gameplay is entered, every screen is entirely different than the main control room. Tactical combat is waged on a screen that is dominated by a space field with ship controls off to the side. The ship's controls are dwarfed by a huge camera-manipulation control array with tiny controls above it. Other similar real-time games have the "camera" controlled by mouse-clicking and dragging, thus removing the necessity for complicated buttons. After all, natural motion maps neatly to this action -- if the player right clicks in say, StarCraft, and holds the button down, and moves the mouse to the right, the camera pans right. Simple, and most importantly to the real-time genre -- it is fast. Rebellion forgoes this obvious and simple control, but to what effect? (Figure Seven)